From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229729AbhBHWvn (ORCPT ); Mon, 8 Feb 2021 17:51:43 -0500 Received: from mail-oo1-xc2e.google.com (mail-oo1-xc2e.google.com [IPv6:2607:f8b0:4864:20::c2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F3F1C06178C for ; Mon, 8 Feb 2021 14:51:03 -0800 (PST) Received: by mail-oo1-xc2e.google.com with SMTP id x23so3846986oop.1 for ; Mon, 08 Feb 2021 14:51:03 -0800 (PST) Date: Mon, 8 Feb 2021 14:50:47 -0800 (PST) From: Hugh Dickins Subject: Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390 In-Reply-To: <20210205160551.cf57c4293ba5ccb8eb648c11@linux-foundation.org> Message-ID: References: <20210205230620.518245-1-seth.forshee@canonical.com> <20210205160551.cf57c4293ba5ccb8eb648c11@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII List-ID: To: Seth Forshee Cc: Andrew Morton , Hugh Dickins , Chris Down , Amir Goldstein , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org On Fri, 5 Feb 2021, Andrew Morton wrote: > On Fri, 5 Feb 2021 17:06:20 -0600 Seth Forshee wrote: > > > This feature requires ino_t be 64-bits, which is true for every > > 64-bit architecture but s390, so prevent this option from being > > selected there. > > > > The previous patch nicely described the end-user impact of the bug. > This is especially important when requesting a -stable backport. > > Here's what I ended up with: > > > From: Seth Forshee > Subject: tmpfs: disallow CONFIG_TMPFS_INODE64 on s390 > > Currently there is an assumption in tmpfs that 64-bit architectures also > have a 64-bit ino_t. This is not true on s390 which has a 32-bit ino_t. > With CONFIG_TMPFS_INODE64=y tmpfs mounts will get 64-bit inode numbers and > display "inode64" in the mount options, but passing the "inode64" mount > option will fail. This leads to the following behavior: > > # mkdir mnt > # mount -t tmpfs nodev mnt > # mount -o remount,rw mnt > mount: /home/ubuntu/mnt: mount point not mounted or bad option. > > As mount sees "inode64" in the mount options and thus passes it in the > options for the remount. > > > So prevent CONFIG_TMPFS_INODE64 from being selected on s390. > > Link: https://lkml.kernel.org/r/20210205230620.518245-1-seth.forshee@canonical.com > Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb") > Signed-off-by: Seth Forshee > Cc: Chris Down > Cc: Hugh Dickins Thank you Seth: now that you've fixed Kirill's alpha observation too, Acked-by: Hugh Dickins > Cc: Amir Goldstein > Cc: Heiko Carstens > Cc: Vasily Gorbik > Cc: Christian Borntraeger > Cc: [5.9+] > Signed-off-by: Andrew Morton > --- > > fs/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/fs/Kconfig~tmpfs-disallow-config_tmpfs_inode64-on-s390 > +++ a/fs/Kconfig > @@ -203,7 +203,7 @@ config TMPFS_XATTR > > config TMPFS_INODE64 > bool "Use 64-bit ino_t by default in tmpfs" > - depends on TMPFS && 64BIT > + depends on TMPFS && 64BIT && !S390 > default n > help > tmpfs has historically used only inode numbers as wide as an unsigned > _ > >